Carburetor for supercharging internal-combustion engines



Oct. 4, 1927.

' F. PORSCHE CARBURETOR FOR SUPERCHARGING INTERNAL COMBUSTION ENGINES Filed March 14. 1925 Patented Oct. 4, 1927.

UNITED STATES PATENT OFFICE.

FERDINAND PORSCHE, F STUTTGART-UNTERTURKHEIM, GERMANY, ASSIGNOR, BY. MESNE ASSIGNMENTS, T0 DAIMLER-BENZ AKTIENGESELLSCHAET, 0F BERLIN,

GERMANY.

GABBURETOR FOR SUPERGI IARGING INTERNAL-COMBUSTION ENGINES.

Application filed March 14, 1925, Serial No.

In internal combustion engines in which the charge is introduced into the engine cylinders under a certain overpressure by means of a blower for the purpose of increasing the weight of the charge with a view to increasing the output, it has heretofore been usual to use for the formation of the explosive mixture carburetors of the usual construction in which the air nozzle for atomizing the liquid fuel is dimensioned for an air speed which results in the most favourable consumption of fuel for the speed of revolutions of the engine at which it most frequently runs.

When such carburetors are used for internal combustion engines charged under pressure it has been found that the efliciency of supply of the carburetor arrangement is very unfavourable and that, in consequence, the efliciency which is intended to be obtained by the charge bein under pressure is far from being attaine The poor degree of efiiciency of the carburetor must'no doubt be attributed to the fact that, in consequence of the increased throttling resistances, re-

sulting from the larger quantity of air which is being introduced, considerable losses occur.

The object of the present invention is to remove these very considerable disadvantages in internal combustion engines with charge under pressure. I

. The invention depends for its novelty u on the fact that, in order to reduce the thrott mg resistances which are prejudicial to the degree of supply of the carburetor and consequently to the ,output' of the internal combustion engine, the air nozzle isenlarged and formed in such a manner that it adapts itself I in the most favourable manner andto the fullest extent to the conditions prevailing when working the engine with and without the blower.

The modification of the nozzle in accordance with the invention finds its justification I in the following considerations and ascertained facts. An enlargement of the nozzle can be effected, without in any way prejudicing the formation of gas, if the carburetor is fitted in advance of the blower, in relation to the diiection of the flow of the mixture,

so that the blower draws in the air from the atmos here through the carburetor.

' In the c arge under pressure, for instance,

15,690, and in Germany December 24, 1923.

there is drawn in 'a volume of air of approximately l times the amount of the volume of the cylinder of the engine swept by piston. If, therefore, for the engine with blower, a carburetor is used the nozzle of which has a cross section corresponding to that of a carburetor of an engine of the same size without blower, a volume of air 1 times as large must be drawn in through this narrow cross section in the same eriod of time (assuming an equal number 0 revolutions). The speed of flow is consequently considerably greater and the greater resistances thereby arising cause the losses which pfoduce a diminution of thedegree of sup- P ya In accordance withthe present invention the cross section of the nozzleof the carburetor is increased to such an extent that 1 times the volume of cylinder swept by the piston is drawn into the carburetor approximately at the same velocity as such volume in the case of an engine of the same size without blower. The air nozzle of the carburetor may, however, be enlarged beyond the dimension which results from the increased volume of air drawn in when'working with a blower. The further enlargement can be effected because the blower itself contributes to the mixing of the fuel with theair, so

that it is not necessary for such a far reachingatomizing to take place in the air nozzle 35 as is the case with a carburetor without blower or in carburetors through which the combustion air is forced.

The sucking of the c mbustion air through the carburetor by means of the blower is so advantageous .for the filling also, for the reason that the air'reaches the carburetor in a cold and consequently in a dense condition.

In the accompanying drawing two examples of execution are represented in five figures i Figure 1 shows an internal combustion engine with blower and the carburetor placed in advance of the blower, the driving arrangement for the blower and the carburetor being shown in section. Figure 2 is a plan of the same in which the blower is shown in section. Figure 3 also shows a lan of the blower thisexa-mple of execution eing'distinguished 105 from that shown in Figure 2 by the fact that 4O I with the pressure pipe or of the blower. A.-

the suction and pressure pipes are connected admission of t e mixture is connected in the well known manner with the workin cylinders of the internal combustion engine I), and the pipe 1 is further connected with the blower c, of any well. known or suitable type The. latter sucks the mixture through t carburetor d. Theblo'wer 0 is driven from the engine crank shaft e by a coupling 7 and toothed wheels h and i.

- The invention includes the application of the blower according 'to which the blower is running without interruption during the working of the internal combustion engine and conveys the charge into the internal combustion engine, as well as the application of the blower,.in which the blower from time to time only, during the working of the in- I ternal combustion engine, conveys the charge into the internal combustion engine, whilst,

'when the'blower is out of action, the charge reaches the-engine through a by-pass through the suction efl'ect of the working pistons.

By way of example an arrangement for the application of the blower as last mentioned is shown in Figure 3. -A-branch pipe Zconnects the suction pipe is of the blower c throttle valve n is inserted in the said branch pipe and this valve is kept shut whilst the charge is passed through the blower and is opened when the blower is shut 0E. The quantity of air whichis introduced into the engine in consequence of the previous compression amounts to approximately one and a half times the volume of cylinder swept by piston of the engine. In order, therefore, to introduce this volume under approximately the same speed as the volume ofcylinder of an engine of the'same size without blower, the cross section of the nozzle of the carburetor' in advance of the blower may be.

larger in correspondence with the larger volume of air. The cross section of the carburetor in this case may bedurther increased in consequence ofthe fact that the vapourizing of the fuel is assistedby the rotary blower and because itis, therefore, not necessary to maintain thespeed in the air nozzle of the carburetor as great as in carburetors for engines of the same size without blower; In FiguresA and 5 a carburetor of special aeaacee construction is represented. This carburetor has, for instance, three difierent air nozzles 0, go and g The air nozzle 0 which surrounds the mouth of the fuel nozzle r is so dimensioned that the air must pass through the same with the greatest speed. The surrounding nozzles go and g are of larger sections, so that the speeds of the current of air decrease by stages. In consequence. of the fact that a portion of the volume of air which is sucked in always passes the mouth of the fuel nozzle at a speed suliicient for the proper atomizing, it is possible to conduct the air currents through the larger nozzles at a slower speed. In consequence of this arrangement the total cross section for the air streaming through, which is formed by the ,several'nozz'les, ma be larger than in the case of carburetors or an engine of the same size but fitted with one air nozzle onl If such a carburetor is, however, connects with the suction ppm of the blower it will be possible to make t e cross section of the nozzle considerably larger than in carburetors of the known pattern for engines of the same size without blower. It is not impossible to triple the area of cross section as compared with the known carburetors. In quence of this, the resistance to the current becomes of course considerably smaller and the filling is accordingly better.

In order that a carburetor with several air nozzles may also be used with good efiect for working without the blower, the nozzles p and g are, for instance, inserted in the casing of the carburetor in such a manner that they can be shifted relatively to each other and to the nozzle 0. g

In Figure 5 the nozzles are drawn in the position which they assume, for instancel'm the state of rest. In that case the surroundconseing ducts are shut oif, so that, whenthe en-' gine is started, the combustion air streams in only through the nozzle 0. The further nozzles p and g may be of different welghts, so that, with the increasing suction efiect, they are lifted automatically one after the other andthus increase the air cross sectionaccordingly. I The arrangement of nozzles for carburetors of internal combustion engines with blower above described is to be considered as an example of execution for realizing the. invention. The shape, number and arrangement of the nozzles can be selected asmay appear most suitable and details of construction may be varied as found desirable. What I claim is In combination, an engine, a carburetor, a I

branched mixture conduit from said carburetor to said englne, a supercharger 1n one of said branches, means for selectlvelysubjecting the carburetor to the suction of thesupercharger or of the engine, through said respective branches, and suction opened air valves coo rating to. occlude the air intake intake is automatically increased upon the of the car uretor, said air valves being reselective use of the su 'rcharger to avoid sponsive, the one, to a range of sub-pressures throttling of the air in noted by said super-4 10 up to the maximum engine-induced suction, charger.

5 and the other,.t0 a range of sub-pressures ex- In testimony whereof I aflix my signature.

tending beyond said maximum, whereby the cross-sectional capacity of the carburetor air FEEDINAND PORSCHE. 

